Manage your subscription

A brain primed for violence?

By Helen Phillips

PEOPLE with a gene variant known to be linked to aggression may have been born with key brain differences that could make them more likely to snap under pressure.

The gene, called MAOA, produces the enzyme monoamine oxidase-A. Complete absence of this gene, though rare in humans, has been linked to aggressive behaviour in men, and mice engineered to lack MAOA are also unusually aggressive.

Many more people, however, carry a low-activity variant of the gene, known as MAOA-L. A study in 2002 found that men with MAOA-L who had been maltreated as children were …